The present invention relates in general to industrial filters, particularly for lubricating and cooling liquids for machine tools and the like.
More particularly, the invention relates to a self-cleaning vacuum filter with a permanent, endless filter medium, including a tank for the liquid to be filtered containing a filter bed which communicates interiorly with a vacuum chamber connected to means for drawing the liquid through the filter medium, and in which the filter bed includes a screen and an endless loop of regenerable filter fabric having return rollers and movable in steps, by motor-driven entrainment means, over the screen and through a station for the removal of the filtered material emerging from the tank.
The main problem connected with filters of this type results from the difficulties of separating and removing the filtered material from the filter fabric and the consequent difficulty of effectively regenerating the fabric. In particular, in known filters of the type specified above, the path of the filter fabric is such that its surface on which the filtered material is deposited normally faces inwardly of the loop so that, in the regions where it passes over the return rollers, the filtered material is squashed and compacted against the fabric, forming a very tenacious, pasty layer which is not at all easy to remove.